Implement optimized send

9 files changed, 247 insertions, 73 deletions

diff --git a/lib/ruby_vm/mjit/assembler.rb b/lib/ruby_vm/mjit/assembler.rb
index abf0ae6c08..989d069776 100644
--- a/lib/ruby_vm/mjit/assembler.rb
+++ b/lib/ruby_vm/mjit/assembler.rb
@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 module RubyVM::MJIT
+  # 8-bit memory access
+  class BytePtr < Data.define(:reg, :disp); end
+
   # 32-bit memory access
   class DwordPtr < Data.define(:reg, :disp); end
 
@@ -66,7 +69,7 @@ module RubyVM::MJIT
     def add(dst, src)
       case [dst, src]
       # ADD r/m64, imm8 (Mod 00: [reg])
-      in [[Symbol => dst_reg], Integer => src_imm] if r64?(dst_reg) && imm8?(src_imm)
+      in [Array[Symbol => dst_reg], Integer => src_imm] if r64?(dst_reg) && imm8?(src_imm)
         # REX.W + 83 /0 ib
         # MI: Operand 1: ModRM:r/m (r, w), Operand 2: imm8/16/32
         insn(
@@ -132,7 +135,7 @@ module RubyVM::MJIT
           imm: imm32(src_imm),
         )
       # AND r64, r/m64 (Mod 01: [reg]+disp8)
-      in [Symbol => dst_reg, [Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
+      in [Symbol => dst_reg, Array[Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
         # REX.W + 23 /r
         # RM: Operand 1: ModRM:reg (r, w), Operand 2: ModRM:r/m (r)
         insn(
@@ -274,7 +277,7 @@ module RubyVM::MJIT
           mod_rm: ModRM[mod: Mod11, reg: dst_reg, rm: src_reg],
         )
       # CMOVZ r64, r/m64 (Mod 01: [reg]+disp8)
-      in [Symbol => dst_reg, [Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
+      in [Symbol => dst_reg, Array[Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
         # REX.W + 0F 44 /r
         # RM: Operand 1: ModRM:reg (r, w), Operand 2: ModRM:r/m (r)
         insn(
@@ -290,6 +293,16 @@ module RubyVM::MJIT
 
     def cmp(left, right)
       case [left, right]
+      # CMP r/m8, imm8 (Mod 01: [reg]+disp8)
+      in [BytePtr[reg: left_reg, disp: left_disp], Integer => right_imm] if r64?(left_reg) && imm8?(left_disp) && imm8?(right_imm)
+        # 80 /7 ib
+        # MI: Operand 1: ModRM:r/m (r), Operand 2: imm8/16/32
+        insn(
+          opcode: 0x80,
+          mod_rm: ModRM[mod: Mod01, reg: 7, rm: left_reg],
+          disp: left_disp,
+          imm: imm8(right_imm),
+        )
       # CMP r/m32, imm32 (Mod 01: [reg]+disp8)
       in [DwordPtr[reg: left_reg, disp: left_disp], Integer => right_imm] if imm8?(left_disp) && imm32?(right_imm)
         # 81 /7 id
@@ -301,7 +314,7 @@ module RubyVM::MJIT
           imm: imm32(right_imm),
         )
       # CMP r/m64, imm8 (Mod 01: [reg]+disp8)
-      in [[Symbol => left_reg, Integer => left_disp], Integer => right_imm] if r64?(left_reg) && imm8?(left_disp) && imm8?(right_imm)
+      in [Array[Symbol => left_reg, Integer => left_disp], Integer => right_imm] if r64?(left_reg) && imm8?(left_disp) && imm8?(right_imm)
         # REX.W + 83 /7 ib
         # MI: Operand 1: ModRM:r/m (r), Operand 2: imm8/16/32
         insn(
@@ -321,8 +334,18 @@ module RubyVM::MJIT
           mod_rm: ModRM[mod: Mod11, reg: 7, rm: left_reg],
           imm: imm8(right_imm),
         )
+      # CMP r/m64, imm32 (Mod 11: reg)
+      in [Symbol => left_reg, Integer => right_imm] if r64?(left_reg) && imm32?(right_imm)
+        # REX.W + 81 /7 id
+        # MI: Operand 1: ModRM:r/m (r), Operand 2: imm8/16/32
+        insn(
+          prefix: REX_W,
+          opcode: 0x81,
+          mod_rm: ModRM[mod: Mod11, reg: 7, rm: left_reg],
+          imm: imm32(right_imm),
+        )
       # CMP r/m64, r64 (Mod 01: [reg]+disp8)
-      in [[Symbol => left_reg, Integer => left_disp], Symbol => right_reg] if r64?(right_reg)
+      in [Array[Symbol => left_reg, Integer => left_disp], Symbol => right_reg] if r64?(right_reg)
         # REX.W + 39 /r
         # MR: Operand 1: ModRM:r/m (r), Operand 2: ModRM:reg (r)
         insn(
@@ -393,7 +416,7 @@ module RubyVM::MJIT
         # E9 cd
         insn(opcode: 0xe9, imm: rel32(dst_addr))
       # JMP r/m64 (Mod 01: [reg]+disp8)
-      in [Symbol => dst_reg, Integer => dst_disp] if imm8?(dst_disp)
+      in Array[Symbol => dst_reg, Integer => dst_disp] if imm8?(dst_disp)
         # FF /4
         insn(opcode: 0xff, mod_rm: ModRM[mod: Mod01, reg: 4, rm: dst_reg], disp: dst_disp)
       # JMP r/m64 (Mod 11: reg)
@@ -456,7 +479,7 @@ module RubyVM::MJIT
     def lea(dst, src)
       case [dst, src]
       # LEA r64,m (Mod 01: [reg]+disp8)
-      in [Symbol => dst_reg, [Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
+      in [Symbol => dst_reg, Array[Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
         # REX.W + 8D /r
         # RM: Operand 1: ModRM:reg (w), Operand 2: ModRM:r/m (r)
         insn(
@@ -466,7 +489,7 @@ module RubyVM::MJIT
           disp: imm8(src_disp),
         )
       # LEA r64,m (Mod 10: [reg]+disp32)
-      in [Symbol => dst_reg, [Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm32?(src_disp)
+      in [Symbol => dst_reg, Array[Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm32?(src_disp)
         # REX.W + 8D /r
         # RM: Operand 1: ModRM:reg (w), Operand 2: ModRM:r/m (r)
         insn(
@@ -485,7 +508,7 @@ module RubyVM::MJIT
       in Symbol => dst_reg
         case src
         # MOV r64, r/m64 (Mod 00: [reg])
-        in [Symbol => src_reg] if r64?(dst_reg) && r64?(src_reg)
+        in Array[Symbol => src_reg] if r64?(dst_reg) && r64?(src_reg)
           # REX.W + 8B /r
           # RM: Operand 1: ModRM:reg (w), Operand 2: ModRM:r/m (r)
           insn(
@@ -494,7 +517,7 @@ module RubyVM::MJIT
             mod_rm: ModRM[mod: Mod00, reg: dst_reg, rm: src_reg],
           )
         # MOV r64, r/m64 (Mod 01: [reg]+disp8)
-        in [Symbol => src_reg, Integer => src_disp] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
+        in Array[Symbol => src_reg, Integer => src_disp] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
           # REX.W + 8B /r
           # RM: Operand 1: ModRM:reg (w), Operand 2: ModRM:r/m (r)
           insn(
@@ -504,7 +527,7 @@ module RubyVM::MJIT
             disp: src_disp,
           )
         # MOV r64, r/m64 (Mod 10: [reg]+disp16)
-        in [Symbol => src_reg, Integer => src_disp] if r64?(dst_reg) && r64?(src_reg) && imm32?(src_disp)
+        in Array[Symbol => src_reg, Integer => src_disp] if r64?(dst_reg) && r64?(src_reg) && imm32?(src_disp)
           # REX.W + 8B /r
           # RM: Operand 1: ModRM:reg (w), Operand 2: ModRM:r/m (r)
           insn(
@@ -523,7 +546,7 @@ module RubyVM::MJIT
             mod_rm: ModRM[mod: Mod11, reg: dst_reg, rm: src_reg],
           )
         # MOV r32 r/m32 (Mod 01: [reg]+disp8)
-        in [Symbol => src_reg, Integer => src_disp] if r32?(dst_reg) && imm8?(src_disp)
+        in Array[Symbol => src_reg, Integer => src_disp] if r32?(dst_reg) && imm8?(src_disp)
           # 8B /r
           # RM: Operand 1: ModRM:reg (w), Operand 2: ModRM:r/m (r)
           insn(
@@ -563,7 +586,7 @@ module RubyVM::MJIT
         else
           raise NotImplementedError, "mov: not-implemented operands: #{dst.inspect}, #{src.inspect}"
         end
-      in [Symbol => dst_reg]
+      in Array[Symbol => dst_reg]
         case src
         # MOV r/m64, imm32 (Mod 00: [reg])
         in Integer => src_imm if r64?(dst_reg) && imm32?(src_imm)
@@ -587,7 +610,7 @@ module RubyVM::MJIT
         else
           raise NotImplementedError, "mov: not-implemented operands: #{dst.inspect}, #{src.inspect}"
         end
-      in [Symbol => dst_reg, Integer => dst_disp]
+      in Array[Symbol => dst_reg, Integer => dst_disp]
         # Optimize encoding when disp is 0
         return mov([dst_reg], src) if dst_disp == 0
 
@@ -645,7 +668,7 @@ module RubyVM::MJIT
     def or(dst, src)
       case [dst, src]
       # OR r64, r/m64 (Mod 01: [reg]+disp8)
-      in [Symbol => dst_reg, [Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
+      in [Symbol => dst_reg, Array[Symbol => src_reg, Integer => src_disp]] if r64?(dst_reg) && r64?(src_reg) && imm8?(src_disp)
         # REX.W + 0B /r
         # RM: Operand 1: ModRM:reg (r, w), Operand 2: ModRM:r/m (r)
         insn(
@@ -734,7 +757,7 @@ module RubyVM::MJIT
     def test(left, right)
       case [left, right]
       # TEST r/m8*, imm8 (Mod 01: [reg]+disp8)
-      in [[Symbol => left_reg, Integer => left_disp], Integer => right_imm] if imm8?(right_imm) && right_imm >= 0
+      in [Array[Symbol => left_reg, Integer => left_disp], Integer => right_imm] if imm8?(right_imm) && right_imm >= 0
         # REX + F6 /0 ib
         # MI: Operand 1: ModRM:r/m (r), Operand 2: imm8/16/32
         insn(
@@ -744,7 +767,7 @@ module RubyVM::MJIT
           imm: imm8(right_imm),
         )
       # TEST r/m64, imm32 (Mod 01: [reg]+disp8)
-      in [[Symbol => left_reg, Integer => left_disp], Integer => right_imm] if imm32?(right_imm)
+      in [Array[Symbol => left_reg, Integer => left_disp], Integer => right_imm] if imm32?(right_imm)
         # REX.W + F7 /0 id
         # MI: Operand 1: ModRM:r/m (r), Operand 2: imm8/16/32
         insn(
diff --git a/lib/ruby_vm/mjit/compiler.rb b/lib/ruby_vm/mjit/compiler.rb
index 5aac3626fa..b34df4c392 100644
--- a/lib/ruby_vm/mjit/compiler.rb
+++ b/lib/ruby_vm/mjit/compiler.rb
@@ -170,6 +170,17 @@ module RubyVM::MJIT
         insn = self.class.decode_insn(iseq.body.iseq_encoded[index])
         jit.pc = (iseq.body.iseq_encoded + index).to_i
 
+        # If previous instruction requested to record the boundary
+        if jit.record_boundary_patch_point
+          # Generate an exit to this instruction and record it
+          exit_pos = Assembler.new.then do |ocb_asm|
+            @exit_compiler.compile_side_exit(jit.pc, ctx, ocb_asm)
+            @ocb.write(ocb_asm)
+          end
+          Invariants.record_global_inval_patch(asm, exit_pos)
+          jit.record_boundary_patch_point = false
+        end
+
         case status = @insn_compiler.compile(jit, ctx, asm, insn)
         when KeepCompiling
           index += insn.len
@@ -177,7 +188,7 @@ module RubyVM::MJIT
           # TODO: pad nops if entry exit exists
           break
         when CantCompile
-          @exit_compiler.compile_side_exit(jit, ctx, asm)
+          @exit_compiler.compile_side_exit(jit.pc, ctx, asm)
           break
         else
           raise "compiling #{insn.name} returned unexpected status: #{status.inspect}"
diff --git a/lib/ruby_vm/mjit/exit_compiler.rb b/lib/ruby_vm/mjit/exit_compiler.rb
index 20645fdb9e..bf85a340d7 100644
--- a/lib/ruby_vm/mjit/exit_compiler.rb
+++ b/lib/ruby_vm/mjit/exit_compiler.rb
@@ -63,15 +63,15 @@ module RubyVM::MJIT
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def compile_side_exit(jit, ctx, asm)
+    def compile_side_exit(pc, ctx, asm)
       # Increment per-insn exit counter
-      incr_insn_exit(jit.pc, asm)
+      incr_insn_exit(pc, asm)
 
       # Fix pc/sp offsets for the interpreter
-      save_pc_and_sp(jit.pc, ctx.dup, asm) # dup to avoid sp_offset update
+      save_pc_and_sp(pc, ctx.dup, asm) # dup to avoid sp_offset update
 
       # Restore callee-saved registers
-      asm.comment("exit to interpreter on #{pc_to_insn(jit.pc).name}")
+      asm.comment("exit to interpreter on #{pc_to_insn(pc).name}")
       asm.pop(SP)
       asm.pop(EC)
       asm.pop(CFP)
diff --git a/lib/ruby_vm/mjit/insn_compiler.rb b/lib/ruby_vm/mjit/insn_compiler.rb
index 1df6809c2b..a06030fd6f 100644
--- a/lib/ruby_vm/mjit/insn_compiler.rb
+++ b/lib/ruby_vm/mjit/insn_compiler.rb
@@ -966,7 +966,7 @@ module RubyVM::MJIT
         recv_opnd = ctx.stack_opnd(1)
 
         not_array_exit = counted_exit(side_exit, :optaref_recv_not_array)
-        if jit_guard_known_class(jit, ctx, asm, comptime_recv.class, recv_opnd, comptime_recv, not_array_exit) == CantCompile
+        if jit_guard_known_klass(jit, ctx, asm, comptime_recv.class, recv_opnd, comptime_recv, not_array_exit) == CantCompile
           return CantCompile
         end
 
@@ -1001,7 +1001,7 @@ module RubyVM::MJIT
 
         # Guard that the receiver is a Hash
         not_hash_exit = counted_exit(side_exit, :optaref_recv_not_hash)
-        if jit_guard_known_class(jit, ctx, asm, comptime_recv.class, recv_opnd, comptime_recv, not_hash_exit) == CantCompile
+        if jit_guard_known_klass(jit, ctx, asm, comptime_recv.class, recv_opnd, comptime_recv, not_hash_exit) == CantCompile
           return CantCompile
         end
 
@@ -1051,12 +1051,12 @@ module RubyVM::MJIT
         side_exit = side_exit(jit, ctx)
 
         # Guard receiver is an Array
-        if jit_guard_known_class(jit, ctx, asm, comptime_recv.class, recv, comptime_recv, side_exit) == CantCompile
+        if jit_guard_known_klass(jit, ctx, asm, comptime_recv.class, recv, comptime_recv, side_exit) == CantCompile
           return CantCompile
         end
 
         # Guard key is a fixnum
-        if jit_guard_known_class(jit, ctx, asm, comptime_key.class, key, comptime_key, side_exit) == CantCompile
+        if jit_guard_known_klass(jit, ctx, asm, comptime_key.class, key, comptime_key, side_exit) == CantCompile
           return CantCompile
         end
 
@@ -1090,7 +1090,7 @@ module RubyVM::MJIT
         side_exit = side_exit(jit, ctx)
 
         # Guard receiver is a Hash
-        if jit_guard_known_class(jit, ctx, asm, comptime_recv.class, recv, comptime_recv, side_exit) == CantCompile
+        if jit_guard_known_klass(jit, ctx, asm, comptime_recv.class, recv, comptime_recv, side_exit) == CantCompile
           return CantCompile
         end
 
@@ -1425,7 +1425,7 @@ module RubyVM::MJIT
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_guard_known_class(jit, ctx, asm, known_klass, obj_opnd, comptime_obj, side_exit, limit: 5)
+    def jit_guard_known_klass(jit, ctx, asm, known_klass, obj_opnd, comptime_obj, side_exit, limit: 5)
       # Only memory operand is supported for now
       assert_equal(true, obj_opnd.is_a?(Array))
 
@@ -1445,9 +1445,13 @@ module RubyVM::MJIT
         asm.comment('guard object is fixnum')
         asm.test(obj_opnd, C.RUBY_FIXNUM_FLAG)
         jit_chain_guard(:jz, jit, ctx, asm, side_exit, limit:)
-      elsif known_klass == Symbol
-        asm.incr_counter(:send_guard_symbol)
-        return CantCompile
+      elsif known_klass == Symbol && static_symbol?(comptime_obj)
+        # We will guard STATIC vs DYNAMIC as though they were separate classes
+        # DYNAMIC symbols can be handled by the general else case below
+        asm.comment('guard object is static symbol')
+        assert_equal(8, C.RUBY_SPECIAL_SHIFT)
+        asm.cmp(BytePtr[*obj_opnd], C.RUBY_SYMBOL_FLAG)
+        jit_chain_guard(:jne, jit, ctx, asm, side_exit, limit:)
       elsif known_klass == Float
         asm.incr_counter(:send_guard_float)
         return CantCompile
@@ -1471,7 +1475,7 @@ module RubyVM::MJIT
 
         # Bail if receiver class is different from known_klass
         klass_opnd = [obj_opnd, C.RBasic.offsetof(:klass)]
-        asm.comment('guard known class')
+        asm.comment("guard known class #{known_klass}")
         asm.mov(:rcx, to_value(known_klass))
         asm.cmp(klass_opnd, :rcx)
         jit_chain_guard(:jne, jit, ctx, asm, side_exit, limit:)
@@ -1593,7 +1597,7 @@ module RubyVM::MJIT
         end
 
         # Guard that a is a String
-        if jit_guard_known_class(jit, ctx, asm, comptime_a.class, a_opnd, comptime_a, side_exit) == CantCompile
+        if jit_guard_known_klass(jit, ctx, asm, comptime_a.class, a_opnd, comptime_a, side_exit) == CantCompile
           return false
         end
 
@@ -1609,7 +1613,7 @@ module RubyVM::MJIT
         # Otherwise guard that b is a T_STRING (from type info) or String (from runtime guard)
         # Note: any T_STRING is valid here, but we check for a ::String for simplicity
         # To pass a mutable static variable (rb_cString) requires an unsafe block
-        if jit_guard_known_class(jit, ctx, asm, comptime_b.class, b_opnd, comptime_b, side_exit) == CantCompile
+        if jit_guard_known_klass(jit, ctx, asm, comptime_b.class, b_opnd, comptime_b, side_exit) == CantCompile
           return false
         end
 
@@ -1639,6 +1643,7 @@ module RubyVM::MJIT
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
     def jit_prepare_routine_call(jit, ctx, asm)
+      jit.record_boundary_patch_point = true
       jit_save_pc(jit, asm)
       jit_save_sp(jit, ctx, asm)
     end
@@ -1672,6 +1677,17 @@ module RubyVM::MJIT
       reset_depth.chain_depth = 0
 
       next_pc = jit.pc + jit.insn.len * C.VALUE.size
+
+      # We are at the end of the current instruction. Record the boundary.
+      if jit.record_boundary_patch_point
+        exit_pos = Assembler.new.then do |ocb_asm|
+          @exit_compiler.compile_side_exit(next_pc, ctx, ocb_asm)
+          @ocb.write(ocb_asm)
+        end
+        Invariants.record_global_inval_patch(asm, exit_pos)
+        jit.record_boundary_patch_point = false
+      end
+
       stub_next_block(jit.iseq, next_pc, reset_depth, asm, comment: 'jump_to_next_insn')
     end
 
@@ -1781,7 +1797,8 @@ module RubyVM::MJIT
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_method(jit, ctx, asm, mid, argc, flags)
+    # @param send_shift [Integer] The number of shifts needed for VM_CALL_OPT_SEND
+    def jit_call_method(jit, ctx, asm, mid, argc, flags, send_shift: 0)
       # Specialize on a compile-time receiver, and split a block for chain guards
       unless jit.at_current_insn?
         defer_compilation(jit, ctx, asm)
@@ -1791,22 +1808,22 @@ module RubyVM::MJIT
       # Generate a side exit
       side_exit = side_exit(jit, ctx)
 
-      # Calculate a receiver index
+      # kw_splat is not supported yet
       if flags & C.VM_CALL_KW_SPLAT != 0
-        # recv_index calculation may not work for this
         asm.incr_counter(:send_kw_splat)
         return CantCompile
       end
-      recv_index = argc # TODO: +1 for VM_CALL_ARGS_BLOCKARG
 
       # Get a compile-time receiver and its class
-      comptime_recv = jit.peek_at_stack(recv_index)
+      recv_idx = argc + (flags & C.VM_CALL_ARGS_BLOCKARG != 0 ? 1 : 0)
+      recv_idx += send_shift
+      comptime_recv = jit.peek_at_stack(recv_idx)
       comptime_recv_klass = C.rb_class_of(comptime_recv)
 
       # Guard the receiver class (part of vm_search_method_fastpath)
-      recv_opnd = ctx.stack_opnd(recv_index)
+      recv_opnd = ctx.stack_opnd(recv_idx)
       megamorphic_exit = counted_exit(side_exit, :send_klass_megamorphic)
-      if jit_guard_known_class(jit, ctx, asm, comptime_recv_klass, recv_opnd, comptime_recv, megamorphic_exit) == CantCompile
+      if jit_guard_known_klass(jit, ctx, asm, comptime_recv_klass, recv_opnd, comptime_recv, megamorphic_exit) == CantCompile
         return CantCompile
       end
 
@@ -1838,27 +1855,27 @@ module RubyVM::MJIT
       # Invalidate on redefinition (part of vm_search_method_fastpath)
       Invariants.assume_method_lookup_stable(jit, cme)
 
-      jit_call_method_each_type(jit, ctx, asm, argc, flags, cme, comptime_recv, recv_opnd)
+      jit_call_method_each_type(jit, ctx, asm, argc, flags, cme, comptime_recv, recv_opnd, send_shift:)
     end
 
     # vm_call_method_each_type
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_method_each_type(jit, ctx, asm, argc, flags, cme, comptime_recv, recv_opnd)
+    def jit_call_method_each_type(jit, ctx, asm, argc, flags, cme, comptime_recv, recv_opnd, send_shift:)
       case cme.def.type
       when C.VM_METHOD_TYPE_ISEQ
-        jit_call_iseq_setup(jit, ctx, asm, cme, flags, argc)
+        jit_call_iseq_setup(jit, ctx, asm, cme, flags, argc, send_shift:)
       when C.VM_METHOD_TYPE_NOTIMPLEMENTED
         asm.incr_counter(:send_notimplemented)
         return CantCompile
       when C.VM_METHOD_TYPE_CFUNC
-        jit_call_cfunc(jit, ctx, asm, cme, flags, argc)
+        jit_call_cfunc(jit, ctx, asm, cme, flags, argc, send_shift:)
       when C.VM_METHOD_TYPE_ATTRSET
         asm.incr_counter(:send_attrset)
         return CantCompile
       when C.VM_METHOD_TYPE_IVAR
-        jit_call_ivar(jit, ctx, asm, cme, flags, argc, comptime_recv, recv_opnd)
+        jit_call_ivar(jit, ctx, asm, cme, flags, argc, comptime_recv, recv_opnd, send_shift:)
       when C.VM_METHOD_TYPE_MISSING
         asm.incr_counter(:send_missing)
         return CantCompile
@@ -1869,7 +1886,7 @@ module RubyVM::MJIT
         asm.incr_counter(:send_alias)
         return CantCompile
       when C.VM_METHOD_TYPE_OPTIMIZED
-        jit_call_optimized(jit, ctx, asm, cme, flags, argc)
+        jit_call_optimized(jit, ctx, asm, cme, flags, argc, send_shift:)
       when C.VM_METHOD_TYPE_UNDEF
         asm.incr_counter(:send_undef)
         return CantCompile
@@ -1889,7 +1906,7 @@ module RubyVM::MJIT
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_iseq_setup(jit, ctx, asm, cme, flags, argc)
+    def jit_call_iseq_setup(jit, ctx, asm, cme, flags, argc, send_shift:)
       iseq = def_iseq_ptr(cme.def)
       opt_pc = jit_callee_setup_arg(jit, ctx, asm, flags, argc, iseq)
       if opt_pc == CantCompile
@@ -1902,19 +1919,24 @@ module RubyVM::MJIT
         asm.incr_counter(:send_tailcall)
         return CantCompile
       end
-      jit_call_iseq_setup_normal(jit, ctx, asm, cme, flags, argc, iseq)
+      jit_call_iseq_setup_normal(jit, ctx, asm, cme, flags, argc, iseq, send_shift:)
     end
 
     # vm_call_iseq_setup_normal (vm_call_iseq_setup_2 -> vm_call_iseq_setup_normal)
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_iseq_setup_normal(jit, ctx, asm, cme, flags, argc, iseq)
+    def jit_call_iseq_setup_normal(jit, ctx, asm, cme, flags, argc, iseq, send_shift:)
+      # We will not have side exits from here. Adjust the stack.
+      if flags & C.VM_CALL_OPT_SEND != 0
+        jit_call_opt_send_shift_stack(ctx, asm, argc, send_shift:)
+      end
+
       # Save caller SP and PC before pushing a callee frame for backtrace and side exits
       asm.comment('save SP to caller CFP')
-      # Not setting this to SP register. This cfp->sp will be copied to SP on leave insn.
-      sp_index = -(1 + argc) # Pop receiver and arguments for side exits # TODO: subtract one more for VM_CALL_ARGS_BLOCKARG
-      asm.lea(:rax, ctx.sp_opnd(C.VALUE.size * sp_index))
+      recv_idx = argc + (flags & C.VM_CALL_ARGS_BLOCKARG != 0 ? 1 : 0)
+      # Skip setting this to SP register. This cfp->sp will be copied to SP on leave insn.
+      asm.lea(:rax, ctx.sp_opnd(C.VALUE.size * -(1 + recv_idx))) # Pop receiver and arguments to prepare for side exits
       asm.mov([CFP, C.rb_control_frame_t.offsetof(:sp)], :rax)
       jit_save_pc(jit, asm, comment: 'save PC to caller CFP')
 
@@ -1937,7 +1959,7 @@ module RubyVM::MJIT
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_cfunc(jit, ctx, asm, cme, flags, argc)
+    def jit_call_cfunc(jit, ctx, asm, cme, flags, argc, send_shift:)
       if jit_caller_setup_arg(jit, ctx, asm, flags) == CantCompile
         return CantCompile
       end
@@ -1945,14 +1967,14 @@ module RubyVM::MJIT
         return CantCompile
       end
 
-      jit_call_cfunc_with_frame(jit, ctx, asm, cme, flags, argc)
+      jit_call_cfunc_with_frame(jit, ctx, asm, cme, flags, argc, send_shift:)
     end
 
     # jit_call_cfunc_with_frame
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_cfunc_with_frame(jit, ctx, asm, cme, flags, argc)
+    def jit_call_cfunc_with_frame(jit, ctx, asm, cme, flags, argc, send_shift:)
       cfunc = cme.def.body.cfunc
 
       if argc + 1 > 6
@@ -1981,6 +2003,11 @@ module RubyVM::MJIT
         return CantCompile
       end
 
+      # We will not have side exits from here. Adjust the stack.
+      if flags & C.VM_CALL_OPT_SEND != 0
+        jit_call_opt_send_shift_stack(ctx, asm, argc, send_shift:)
+      end
+
       # Check interrupts before SP motion to safely side-exit with the original SP.
       jit_check_ints(jit, ctx, asm)
 
@@ -2026,11 +2053,11 @@ module RubyVM::MJIT
       EndBlock
     end
 
-    # vm_call_ivar
+    # vm_call_ivar (+ part of vm_call_method_each_type)
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_ivar(jit, ctx, asm, cme, flags, argc, comptime_recv, recv_opnd)
+    def jit_call_ivar(jit, ctx, asm, cme, flags, argc, comptime_recv, recv_opnd, send_shift:)
       if flags & C.VM_CALL_ARGS_SPLAT != 0
         asm.incr_counter(:send_ivar_splat)
         return CantCompile
@@ -2041,6 +2068,7 @@ module RubyVM::MJIT
         return CantCompile
       end
 
+      # We don't support jit_call_opt_send_shift_stack for this yet.
       if flags & C.VM_CALL_OPT_SEND != 0
         asm.incr_counter(:send_ivar_opt_send)
         return CantCompile
@@ -2048,7 +2076,7 @@ module RubyVM::MJIT
 
       ivar_id = cme.def.body.attr.id
 
-      if flags & C.VM_CALL_OPT_SEND != 0
+      if flags & C.VM_CALL_ARGS_BLOCKARG != 0
         asm.incr_counter(:send_ivar_blockarg)
         return CantCompile
       end
@@ -2060,11 +2088,10 @@ module RubyVM::MJIT
     # @param jit [RubyVM::MJIT::JITState]
     # @param ctx [RubyVM::MJIT::Context]
     # @param asm [RubyVM::MJIT::Assembler]
-    def jit_call_optimized(jit, ctx, asm, cme, flags, argc)
+    def jit_call_optimized(jit, ctx, asm, cme, flags, argc, send_shift:)
       case cme.def.body.optimized.type
       when C.OPTIMIZED_METHOD_TYPE_SEND
-        asm.incr_counter(:send_optimized_send)
-        return CantCompile
+        jit_call_opt_send(jit, ctx, asm, cme, flags, argc, send_shift:)
       when C.OPTIMIZED_METHOD_TYPE_CALL
         asm.incr_counter(:send_optimized_call)
         return CantCompile
@@ -2083,6 +2110,87 @@ module RubyVM::MJIT
       end
     end
 
+    # vm_call_opt_send
+    # @param jit [RubyVM::MJIT::JITState]
+    # @param ctx [RubyVM::MJIT::Context]
+    # @param asm [RubyVM::MJIT::Assembler]
+    def jit_call_opt_send(jit, ctx, asm, cme, flags, argc, send_shift:)
+      if jit_caller_setup_arg(jit, ctx, asm, flags) == CantCompile
+        return CantCompile
+      end
+
+      if argc == 0
+        asm.incr_counter(:send_optimized_send_no_args)
+        return CantCompile
+      end
+
+      argc -= 1
+      # We aren't handling `send(:send, ...)` yet. This might work, but not tested yet.
+      if send_shift > 0
+        asm.incr_counter(:send_optimized_send_send)
+        return CantCompile
+      end
+      # Ideally, we want to shift the stack here, but it's not safe until you reach the point
+      # where you never exit. `send_shift` signals to lazily shift the stack by this amount.
+      send_shift += 1
+
+      kw_splat = flags & C.VM_CALL_KW_SPLAT != 0
+      jit_call_symbol(jit, ctx, asm, cme, C.VM_CALL_FCALL, argc, kw_splat, send_shift:)
+    end
+
+    # @param ctx [RubyVM::MJIT::Context]
+    # @param asm [RubyVM::MJIT::Assembler]
+    def jit_call_opt_send_shift_stack(ctx, asm, argc, send_shift:)
+      # We don't support `send(:send, ...)` for now.
+      assert_equal(1, send_shift)
+
+      asm.comment('shift stack')
+      (0...argc).reverse_each do |i|
+        opnd = ctx.stack_opnd(i)
+        opnd2 = ctx.stack_opnd(i + 1)
+        asm.mov(:rax, opnd)
+        asm.mov(opnd2, :rax)
+      end
+
+      ctx.stack_pop(1)
+    end
+
+    # vm_call_symbol
+    # @param jit [RubyVM::MJIT::JITState]
+    # @param ctx [RubyVM::MJIT::Context]
+    # @param asm [RubyVM::MJIT::Assembler]
+    def jit_call_symbol(jit, ctx, asm, cme, flags, argc, kw_splat, send_shift:)
+      flags |= C.VM_CALL_OPT_SEND | (kw_splat ? C.VM_CALL_KW_SPLAT : 0)
+
+      comptime_symbol = jit.peek_at_stack(argc)
+      if comptime_symbol.class != String && !static_symbol?(comptime_symbol)
+        asm.incr_counter(:send_optimized_send_not_sym_or_str)
+        return CantCompile
+      end
+
+      mid = C.get_symbol_id(comptime_symbol)
+      if mid == 0
+        asm.incr_counter(:send_optimized_send_null_mid)
+        return CantCompile
+      end
+
+      asm.comment("Guard #{comptime_symbol.inspect} is on stack")
+      mid_changed_exit = counted_exit(side_exit(jit, ctx), :send_optimized_send_mid_changed)
+      if jit_guard_known_klass(jit, ctx, asm, comptime_symbol.class, ctx.stack_opnd(argc), comptime_symbol, mid_changed_exit) == CantCompile
+        return CantCompile
+      end
+      asm.mov(C_ARGS[0], ctx.stack_opnd(argc))
+      asm.call(C.rb_get_symbol_id)
+      asm.cmp(C_RET, mid)
+      jit_chain_guard(:jne, jit, ctx, asm, mid_changed_exit)
+
+      if flags & C.VM_CALL_FCALL != 0
+        return jit_call_method(jit, ctx, asm, mid, argc, flags, send_shift:)
+      end
+
+      raise NotImplementedError # unreachable for now
+    end
+
     # vm_push_frame
     #
     # Frame structure:
@@ -2253,8 +2361,11 @@ module RubyVM::MJIT
     end
 
     def fixnum?(obj)
-      flag = C.RUBY_FIXNUM_FLAG
-      (C.to_value(obj) & flag) == flag
+      (C.to_value(obj) & C.RUBY_FIXNUM_FLAG) == C.RUBY_FIXNUM_FLAG
+    end
+
+    def static_symbol?(obj)
+      (C.to_value(obj) & 0xff) == C.RUBY_SYMBOL_FLAG
     end
 
     # @param jit [RubyVM::MJIT::JITState]
@@ -2296,7 +2407,7 @@ module RubyVM::MJIT
         return side_exit
       end
       asm = Assembler.new
-      @exit_compiler.compile_side_exit(jit, ctx, asm)
+      @exit_compiler.compile_side_exit(jit.pc, ctx, asm)
       jit.side_exits[jit.pc] = @ocb.write(asm)
     end
 
diff --git a/lib/ruby_vm/mjit/jit_state.rb b/lib/ruby_vm/mjit/jit_state.rb
index b90d2f8020..3e5fe996fa 100644
--- a/lib/ruby_vm/mjit/jit_state.rb
+++ b/lib/ruby_vm/mjit/jit_state.rb
@@ -1,12 +1,13 @@
 module RubyVM::MJIT
   class JITState < Struct.new(
-    :iseq,       # @param `RubyVM::MJIT::CPointer::Struct_rb_iseq_t`
-    :pc,         # @param [Integer] The JIT target PC
-    :cfp,        # @param `RubyVM::MJIT::CPointer::Struct_rb_control_frame_t` The JIT source CFP (before MJIT is called)
-    :block,      # @param [RubyVM::MJIT::Block]
-    :side_exits, # @param [Hash{ Integer => Integer }] { PC => address }
+    :iseq,                        # @param `RubyVM::MJIT::CPointer::Struct_rb_iseq_t`
+    :pc,                          # @param [Integer] The JIT target PC
+    :cfp,                         # @param `RubyVM::MJIT::CPointer::Struct_rb_control_frame_t` The JIT source CFP (before MJIT is called)
+    :block,                       # @param [RubyVM::MJIT::Block]
+    :side_exits,                  # @param [Hash{ Integer => Integer }] { PC => address }
+    :record_boundary_patch_point, # @param [TrueClass,FalseClass]
   )
-    def initialize(side_exits: {}, **) = super
+    def initialize(side_exits: {}, record_boundary_patch_point: false, **) = super
 
     def insn
       Compiler.decode_insn(C.VALUE.new(pc).*)
diff --git a/mjit_c.c b/mjit_c.c
index f9f43ffe17..ec2eb4bd9c 100644
--- a/mjit_c.c
+++ b/mjit_c.c
@@ -117,6 +117,7 @@ mjit_for_each_iseq(rb_execution_context_t *ec, VALUE self, VALUE block)
 }
 
 extern bool rb_simple_iseq_p(const rb_iseq_t *iseq);
+extern ID rb_get_symbol_id(VALUE name);
 
 #include "mjit_c.rbinc"
 
diff --git a/mjit_c.h b/mjit_c.h
index 6506c46d52..57228ea961 100644
--- a/mjit_c.h
+++ b/mjit_c.h
@@ -144,13 +144,18 @@ MJIT_RUNTIME_COUNTERS(
     send_ivar_opt_send,
     send_ivar_blockarg,
 
-    send_optimized_send,
     send_optimized_call,
     send_optimized_block_call,
     send_optimized_struct_aref,
     send_optimized_struct_aset,
     send_optimized_unknown_type,
 
+    send_optimized_send_no_args,
+    send_optimized_send_not_sym_or_str,
+    send_optimized_send_mid_changed,
+    send_optimized_send_null_mid,
+    send_optimized_send_send,
+
     send_guard_symbol,
     send_guard_float,
 
diff --git a/mjit_c.rb b/mjit_c.rb
index ef515f5bea..4b5ee5a4e1 100644
--- a/mjit_c.rb
+++ b/mjit_c.rb
@@ -180,6 +180,14 @@ module RubyVM::MJIT # :nodoc: all
       Primitive.cexpr! 'SIZET2NUM((size_t)rb_hash_aset)'
     end
 
+    def get_symbol_id(name)
+      Primitive.cexpr! 'SIZET2NUM((size_t)rb_get_symbol_id(name))'
+    end
+
+    def rb_get_symbol_id
+      Primitive.cexpr! 'SIZET2NUM((size_t)rb_get_symbol_id)'
+    end
+
     #========================================================================================
     #
     # Old stuff
@@ -629,6 +637,14 @@ module RubyVM::MJIT # :nodoc: all
     Primitive.cexpr! %q{ ULONG2NUM(RUBY_IMMEDIATE_MASK) }
   end
 
+  def C.RUBY_SPECIAL_SHIFT
+    Primitive.cexpr! %q{ ULONG2NUM(RUBY_SPECIAL_SHIFT) }
+  end
+
+  def C.RUBY_SYMBOL_FLAG
+    Primitive.cexpr! %q{ ULONG2NUM(RUBY_SYMBOL_FLAG) }
+  end
+
   def C.RUBY_T_ARRAY
     Primitive.cexpr! %q{ ULONG2NUM(RUBY_T_ARRAY) }
   end
@@ -1165,12 +1181,16 @@ module RubyVM::MJIT # :nodoc: all
       send_ivar_splat: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_ivar_splat)")],
       send_ivar_opt_send: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_ivar_opt_send)")],
       send_ivar_blockarg: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_ivar_blockarg)")],
-      send_optimized_send: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_send)")],
       send_optimized_call: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_call)")],
       send_optimized_block_call: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_block_call)")],
       send_optimized_struct_aref: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_struct_aref)")],
       send_optimized_struct_aset: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_struct_aset)")],
       send_optimized_unknown_type: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_unknown_type)")],
+      send_optimized_send_no_args: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_send_no_args)")],
+      send_optimized_send_not_sym_or_str: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_send_not_sym_or_str)")],
+      send_optimized_send_mid_changed: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_send_mid_changed)")],
+      send_optimized_send_null_mid: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_send_null_mid)")],
+      send_optimized_send_send: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_optimized_send_send)")],
       send_guard_symbol: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_guard_symbol)")],
       send_guard_float: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), send_guard_float)")],
       getivar_megamorphic: [CType::Immediate.parse("size_t"), Primitive.cexpr!("OFFSETOF((*((struct rb_mjit_runtime_counters *)NULL)), getivar_megamorphic)")],
diff --git a/tool/mjit/bindgen.rb b/tool/mjit/bindgen.rb
index dc2e76dd68..6e67702ea4 100755
--- a/tool/mjit/bindgen.rb
+++ b/tool/mjit/bindgen.rb
@@ -424,6 +424,8 @@ generator = BindingGenerator.new(
       INVALID_SHAPE_ID
       OBJ_TOO_COMPLEX_SHAPE_ID
       RUBY_FIXNUM_FLAG
+      RUBY_SYMBOL_FLAG
+      RUBY_SPECIAL_SHIFT
       RUBY_IMMEDIATE_MASK
       RARRAY_EMBED_LEN_MASK
       RARRAY_EMBED_LEN_SHIFT